Abstract

Identity-based cryptography is form of public-key cryptography that
does not require users to pre-compute key pairs and obtain
certificates for their public keys. Instead, public keys can be
arbitrary identifiers such as email addresses. This means that the
corresponding private keys are derived, at any time, by a trusted
private key generator.

The idea of signcryption is to provide a method to
encrypt and sign data together in a way that is more efficient than
using an encryption scheme combined with a signature scheme.

We present an identity-based signcryption solution that
we believe is the most efficient, provably-secure scheme of its type
proposed to date. Our scheme admits proofs of security in the random
oracle model under the bilinear Diffie-Hellman assumption using the
definitions proposed by Boyen.